Decreasing the incidence of deep vein thrombosis through the use of prophylaxis

AORN Journal,  Oct, 2006  by David L. Summerfield

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Deep vein thrombosis (DVT) and pulmonary embolism (PE) affect between 200,000 and 600,000 Americans each year. Of those patients who develop a PE, 60,000 to 200,000 will die. (1) Pulmonary embolisms kill more people in the United States today than AIDS or breast cancer. (1) Fatal PEs are one of the most common causes of hospital death in the United States. (2) Many physicians, however, feel that venous thromboembolisms (VTEs) are not a problem in their facilities, resulting in patients not receiving appropriate DVT prophylaxis. (2)

All surgical patients are at risk for developing a DVT, especially if they are immobile. Many orthopedic patients may be at greater risk than other surgical patients because they may be more immobile as a result of their surgery. (3) Patients undergoing total hip replace ment (THR) surgery who do not receive DVT prophylaxis have a DVT rate of 50% to 60%, and the DVT rate is 60% to 85% for patients who undergo total knee replacement (TKR) surgery without prophylactic DVT treatment. (4) When a preoperative thrombosis risk assessment tool is used to identify patients who are at risk for developing a DVT and the appropriate prophylactic intervention is used, the number of DVTs in orthopedic surgical patients can be reduced and many lives potentially can be saved.

What Is a DVT?

A DVT is a blood clot that usually occurs in a deep vein located in the thigh or calf, although they sometimes can form in an upper extremity. The thrombus either partially or completely blocks the flow of blood in the vein. If the thrombus breaks free from the vessel and travels to the lungs, it becomes a PE, which can be a fatal event.

A DVT is caused by several factors. The primary mechanisms for DVT formation are venous stasis, vessel wall injury, and a hypercoagulable state. (4) These three mechanisms are collectively called the Virchow triad, attributed to Rudolf Ludwig Karl Virchow, a German pathologist and statesman born in 1821. (5)

The symptoms for DVTs may include tenderness, pain, swelling, and discoloration or redness in the area of pain. A large problem in discovering DVTs, however, is that often the patient has no symptoms. (6) If the DVT dislodges and becomes a PE, the symptoms may include unexplained shortness of breath, chest pain or palpitations, anxiety or sweating, and coughing up blood. (7)

Preventing DVTs

One way to prevent the formation of DVTs is to use prophylactic strategies. The three main types of DVT prophylaxis include

* chemical prophylaxis,

* mechanical prophylaxis, and

* a combination of chemical and mechanical prophylaxis.

Chemical prophylaxis. Chemical prophylaxis involves using medications to prevent the blood from clotting. Medications such as aspirin, warfarin, enoxaparin, and several types of heparin are used as anticoagulants. These medications can be given before, during, or after surgery. Bleeding can be a complication of anticoagulant prophylaxis, however, so it is not always the optimal treatment for surgical patients. (5)

Mechanical prophylaxis. One way to avoid the complication of bleeding for orthopedic surgical patients is to use mechanical prophylaxis (Figure 1). Mechanical prophylaxis involves using compression devices that are placed on the foot, calf, or thigh and calf. The purpose of the compression device is to intermittently squeeze the foot, calf, or thigh and calf to decrease venous stasis, increase the amount of fibrolysins circulating in the blood, and improve the blood flow velocity in the legs. The effectiveness of pneumatic compression has been noted in numerous articles, (8-12) and foot pumps have been shown to be as effective as low molecular weight heparin against the formation of DVTs after THR and TKR. (4) In a study by Nagahiro et al that included 706 patients undergoing general thoracic surgery, 362 patients were given prophylactic pneumatic compression devices, and none of these patients developed a PP. (9) Of the 344 patients who did not receive pneumatic compression prophylaxis, however, seven developed a PE.

[FIGURE 1 OMITTED]

Although the main benefit of using mechanical prophylaxis is that it does not increase risk of bleeding, the main disadvantage is patient compliance. In a study by Charalambous et al of the use of foot pumps by 29 patients undergoing a THR or TKR, the rate of effective use of foot pumps was only 37.2%. (8) Nurses can help their patients by using mechanical prophylaxis to prevent DVTs and encouraging patients to use them correctly.

DVT Assessment Intervention Strategy

Another method to help reduce the incidence of DVT in orthopedic surgical patients is to develop and institute a DVT assessment intervention strategy. When a surgical patient arrives in the preoperative area, a nurse performs an in depth history to assess the patient for DVT risk (Table 1). The assessment allows the nurse to rate the patient's risk as low, moderate, or high. (13) Patients at low risk for DVT would include surgical patients younger than 40 years of age who have no additional risk factors. If a patient has one risk factor and is having minor surgery or is aged 40 to 60 years and has no other risk factors, then he or she is at moderate risk for DVT. Patients at high risk for DVT include any surgical patient older than 60 years of age, any surgical patient aged 40 to 60 years who has one other risk factor, or any surgical patient who has multiple risk factors. (13)